The present invention relates to a semiconductor laser device suitable for use in a system or apparatus, such as an optical communication system or the like, in which information transmission/reception is executed by use of light.
As semiconductor laser devices used for optical communication or the like, there are buried heterostructure (BH) laser devices having semi-insulating current blocking layers. A laser device in which a current blocking layer is provided to reduce a leakage current not contributing to light emission to thereby reduce the oscillation threshold is shown in a paper by S. Asada et al., in "IEEE Journal of Quantum Electronics", vol. QE-25, pages 1362-1368, (1989). In short, shown is a BH laser in which InGaP layers each constituted by a strained semiconductor having a forbidden band gap wider than that of InP are provided on a substrate and in side walls of a mesa.
On the other hand, known are buried crescent lasers, BH lasers and the like, having a current blocking layer formed by stacking p-type InP layers and n-type InP layers alternately to reduce a leakage current JP-A-51-13588.